1. Field of the Invention
The present invention concerns a man-powered boat propulsion device.
2. Description of the Prior Art
Man-powered boat propulsion devices which have been used traditionally include, for example, Japanese sculls (single-scull) used in Japanese sampans or inshore fishing boats and oars used generally in various passenger boats, cutters, etc.
A boat equipped with a Japanese scull can easily be steered by a skilled person, but it usually takes a long time for a person become skilled in managing such a scull. In addition, there is the problem that the propulsive efficiency of a boat equipped with a scull is not as high as that of a boat equipped with oars.
On the other hand, a boat with oars can be simply steered by anyone, but a single oar stroke requires movement of the entire body, which greatly consumes rower's energy. Further, since oars are disposed on both sides of the boat, they hinder fishing operations, etc. from the boat.
The present inventor has already proposed a boat propulsion device for overcoming the foregoing problems, in Japanese Utility Model Laid Open No. Sho 62-71097.
The boat propulsion device in this prior invention comprises a rotational rod which is extensible at both ends and is rotatable about its center as a support point by a driving device, a connection rod hinged to a shaft rod which is rotatably attached at one end to an extensible end of the rotational rod and which rotates leftward and rightward alternately at its other end accompanying the rotation of the rotational rod, and fin-like propulsion means which is connected to the shaft rod by a gear train and which swings laterally in accordance with the alternate rightward and leftward rotation of the shaft rod.
However, in the boat propulsion device constituted as above, since the rotational rod is adapted to be rotated as a driving shaft by the driving device utilizing a prime mover, and transmit the rotational power to the fin-like propulsion means, it is difficult to manually rotate the rotational rod as the driving shaft.
It is, accordingly, an object of the present invention to overcome the foregoing problems in the prior art and provide a man-powered boat propulsion device that can be used to manually generate a large propulsion power for moving the boat, enables an easy steering operation, improves the boat's turning performance and stopping performance, easily moves the boat astern or ahead, and also can be handled by anyone.